Creating a CIE Standard General Sky Ambient Source

The CIE Standard General Sky Ambient Source allows you to generate a specific distribution for the sky according to a zenith luminance value.

Important: This feature is only available under Speos Premium or Enterprise license.

This sky model is based on the publication of the spatial distribution of daylight - CIE standard general sky ISO 15469:2004(E)/CIE S 011/E:2003 .

To create a CIE Standard General Sky Ambient Source:

  1. From the Light Simulation tab, click Ambient and click CIE Standard General Sky .

    A preview of the sun and the 4 cardinal points appear in the 3D view. The sun's position is computed according to the timezone and location set.

  2. In the 3D view:
    • If you want to modify the Zenith direction (corresponding by default to the Z axis), in the 3D view click and select a line.
    • If you want to modify the North direction (corresponding by default to the Y axis), in the 3D view, click and select a line.
    • or click and select a coordinate system to autofill the Axis System.

    The North direction corresponds to the rotation axis of the earth projected on the ground.

    Note: If you define manually one axis only, the other axis is automatically (and randomly) calculated by Speos in the 3D view. However, the other axis in the Definition panel may not correspond to the axis in the 3D view. Please refer to the axis in the 3D view.
  3. From the CIE type drop-down list, select a sky model.
  4. Set the Luminance of the sky at the zenith.
  5. From the Sun type drop-down list:

    • Select Direction to manually set the sun's position and direction thanks to the manipulators in the 3D view.

    • Select Automatic to automatically calculate the sun position according to the north direction and time zone and location you set.

      1. If you want to set the time and location manually, from the Location drop-down list, select User.

      2. Set the time zone and location of your choice.

  6. Set the Time zone and location:

    • If you want to set the coordinates manually (longitude and latitude), from the Location drop-down list, select User.

    • If you want to use the night sky model, adjust the Date and time.

  7. In Optional or advanced settings , adjust the size of the rays displayed in the 3D view.

The Ambient Source appears in the Simulation panel. In the 3D view, the four cardinal points and a representation of the sun are displayed.